The present invention relates to the technical field of detectors, such as metal detectors, designed for detecting non-authorized objects in a zone having protected access.
More precisely the present invention relates to the field of the metal detectors provided to detect arms in airport or similar other sensitive areas, such as in official offices, Minister Buildings, schools, banks and so on.
Many kinds of metal detectors have been still disclosed.
Most of the metal detectors which are used todays in airport are in the form of a channel or portal comprising two vertical walls housing specific electric coils connected to a control unit, said two vertical walls being connected at their top side by a transverse horizontal beam.
Generally the coils housed in the walls are planar.
Examples of such known metal detectors are disclosed in the following prior art documents FR-2720519, FR-2775350, FR-2780585, FR-2694098, FR-2697919, FR-2698178, FR-2698968, FR-2608286, FR-2610417, FR-2607937, FR-2608286, FR-2607937, U.S. Pat. Nos. 6,362,739, 6,359,582, 6,344,818, 6,342,696, 6,218,830, 5,790,685, 5,680,103, 5,341,126, WO03/032011, US-20010042412, WO98/12573, WO97/50000, WO97/42527, EP-0740822, EP-0490921, WO91/03746, U.S. Pat. No. 5,121,105, WO88/07733, US-20030142853, US-20030128150, U.S. Pat. Nos. 6,507,309, 6,507,278, US-20020130804, U.S. Pat. Nos. 6,359,582, 6,150,810, 6,133,829, 5,726,628, 5,600,303, 5,692,029, 5,689,184, 5,227,800, 5,073,782, 5,039,981, 4,866,439, 4,866,424, 4,263,551, 4,019,053, 4,012,690, 3,971,983, 3,707,672, 4,987,767, 5,109,691, 4,449,115.
In some other metal detectors the coils are not planar but in form of a helicoïdal or spiral winding(s) around a vertical and generally cylindrical support. These metal detectors comprising helicoïdal or spiral winding(s) are generally named “column detectors”. In view of the first cited detectors comprising planar coils, the metal detectors including helicoïdal or spiral winding offer advantages in term of compacity and esthetic.
Examples of column detectors are disclosed in the following prior art documents FR-A-2607937, IT00072791, IT1214991.
The prior art document WO03/069320 discloses a metal detector comprising a metal detection subsystem, a radiation detection system and a presence detection subsystem. All those detection subsystems are aligned one behind another without any advantages in term of compacity. In some circumstances, the device disclosed in WO03/069320 leads to false or not reliable detections.